Effect of Dielectric Material Films on Crystallization Characteristics of Ge_2Sb_2Te_5 Phase-Change Memory Film

摘要

Reduction of the film thickness of phase-change film and the adoption of GeN- or ZrO_2-based dielectric films are both effective in achieving good thermal stability in phase-change optical disks. It was experimentally confirmed that, at a heating rate of 10℃/min, the crystallization temperature T_χ of the Ge_2Sb_2Te_5 amorphous film when sandwiched by ZnS-SiO_2 films markedly increases from 162 to 197 ℃, while the thickness of the Ge_2Sb_2Te_5 film decreases from 10 to 3 nm. T_x also slightly increases when ZnS-SiO_2 films are substituted for GeN-based films (from 162 to 165 ℃) and ZrO_2-based films (from 162 to 167 ℃). At the same time, the activation energy of crystallization is 2.4 eV for both GeN- and ZrO_2-based films, and is higher than 2.2 eV for ZnS-SiO_2 films.